The Republican senator from Florida sits on the Senate Intelligence Committee currently investigating the matter. On Sunday, he spoke with NBC's "Meet the Press," urging people to keep their eyes peeled to the probe and trust that it’s what’s best for the country.

"I think everybody just needs to keep watching this, but take a deep breath too, because the FBI's going to do its job," he said. "The FBI doesn't sit around all day and read tweets."

He continued: "The best thing that can happen for everybody, the president, the country, our institutions of government, is for a full and thorough and credible investigation that reveals everything. That's the best thing that can happen. I really believe that, including for the president.”

In a tweet on Friday, President Donald Trump called the investigation a "witch hunt." Rubio recognized “the president's pretty fired up about this.”

“He, from every pronouncement we have seen, feels very strongly that he did nothing wrong, and he wants people to say that, because he feels very strongly about it,” Rubio said. “That said, that in no way is going to impede any of this work from continuing.”

The Senate Intelligence Committee is looking into how Russians tried to obstruct the U.S. election last year and how they might attempt to do it again in the future. They are also investigating if there were any ties to Trump’s campaign.

Trump has long downplayed Russia's role in the election, and has even questioned findings by U.S. intelligence agencies. But Rubio is certain of interference.

“As far as the general theme of Russia’s interference, look, the president has said he doesn’t believe it. I believe it, and not only do I believe it, I know it. Almost everybody else does,” Rubio said.